Not as much curves as the route "Sofia - Svoge" by PoisoneR
or "Milanovo Road" by infestdead.
But it is a pretty new and good street with
some really nice curves and can be done with a
high speed while watching a nice landscape.
Did it in March 2016 and without any other traffic.

Long mountain road filled with many beautiful landscapes and excellent cornering and asphalt. You will enjoy great views of central Rodopi.Road passes through the most beautiful dams.Velingrad can enjoy spas and rest after a long moto transition in a spa hotel.

A great first class national road.
Tarmac is recently renewed and so are the markings on it.
The road is not used much since there is a highway the bypasses it.
It includes three different mountain passes featuring tight corners
from Saranci to Zlatica and fast ones before Koprivshitsa.
Along the road on your left is the "Stara planina" or "Balkan" mountain.
The whole Balkan Peninsula is named after it.
This gives you some spectacular views.
The road gives you access to lots of passes in the mountain like "Beklemeto", "Shipka",
"Republic's pass" and many, many more.
There is a speed-cam at the gas station after Mirkovo's intersection.

Corners only, with usually nice scenery and some great views over the mountains near Pamporovo, superb Antonivanovci lake. If it wasn't for the rather poor asphalt, I would have rate it an exceptional road for the view and corners. Pay attention to sand on the road, especially after rain, as a good portion of the road does not have rain ditches. Nice to visit: Siroka Laka.

Veliko Tarnovo â€“ Gurkovo is a nice combination of corners, going through the Republika pass (â€œprohodâ€ = pass) at 700 meters altitude, a fun road with no spectacular scenery and excellent asphalt in 2011. Gurkovo to Sliven is boring, mostly straight. Sliven to Stara Reka to Kotel takes you over the Vratnik pass (1,000 meters) and Kotlenski pass (700 meters) with nice scenery and acceptable asphalt.
Good accommodation you may find in Arbanassi (touristic village, located about 2 km. out of Veliko) or in Veliko. You may want to visit Veliko Tarnovo and its fortress, as well as Arbanassi.